#ifndef STAN_MATH_PRIM_SCAL_ERR_CHECK_NOT_NAN_HPP
#define STAN_MATH_PRIM_SCAL_ERR_CHECK_NOT_NAN_HPP

#include <stan/math/prim/scal/meta/length.hpp>
#include <stan/math/prim/scal/meta/is_vector_like.hpp>
#include <stan/math/prim/scal/err/domain_error.hpp>
#include <stan/math/prim/scal/err/domain_error_vec.hpp>
#include <stan/math/prim/scal/fun/value_of_rec.hpp>
#include <stan/math/prim/scal/fun/is_nan.hpp>

namespace stan {
  namespace math {

    namespace {
      template <typename T_y, bool is_vec>
      struct not_nan {
        static bool check(const char* function,
                          const char* name,
                          const T_y& y) {
          if (is_nan(value_of_rec(y)))
            domain_error(function, name, y,
                         "is ", ", but must not be nan!");
          return true;
        }
      };

      template <typename T_y>
      struct not_nan<T_y, true> {
        static bool check(const char* function,
                          const char* name,
                          const T_y& y) {
          for (size_t n = 0; n < stan::length(y); n++) {
            if (is_nan(value_of_rec(stan::get(y, n))))
              domain_error_vec(function, name, y, n,
                               "is ", ", but must not be nan!");
          }
          return true;
        }
      };
    }

    /**
     * Return <code>true</code> if <code>y</code> is not
     * <code>NaN</code>.
     *
     * This function is vectorized and will check each element of
     * <code>y</code>. If any element is <code>NaN</code>, this
     * function will throw an exception.
     *
     * @tparam T_y Type of y
     *
     * @param function Function name (for error messages)
     * @param name Variable name (for error messages)
     * @param y Variable to check
     *
     * @return <code>true</code> if y is not NaN.
     * @throw <code>domain_error</code> if any element of y is NaN.
     */
    template <typename T_y>
    inline bool check_not_nan(const char* function,
                              const char* name,
                              const T_y& y) {
      return not_nan<T_y, is_vector_like<T_y>::value>
        ::check(function, name, y);
    }

  }
}
#endif
